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authorSebastian Hesselbarth <sebastian.hesselbarth@gmail.com>2014-04-24 22:57:25 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-04-25 12:07:34 +0100
commite89f443b182c7a813a60d85dbf22d090231b5e6b (patch)
treec43e0fcc04db4e7cab75de84f7ddf10c217fadb8 /arch
parent7d0656598924b2781fb96cdff566c9f844643fcd (diff)
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ARM: 8040/1: pj4: properly detect existence of iWMMXt coprocessor
commit fdb487f5c961b94486a78fa61fa28b8eff1954ab ("ARM: 8015/1: Add cpu_is_pj4 to distinguish PJ4 because it has some differences with V7") introduced a fix for checking PJ4 cpuid to not use PJ4 specific coprocessor access on non-PJ4 platforms. Unfortunately, this in turn broke Marvell Armada 370/XP, both comprising Marvell PJ4B CPUs without iWMMXt extension. Instead of only checking for cpuid, which may not be sufficient to determine iWMMXt support, the presence of iWMMXt coprocessors can be checked by enabling and reading the Coprocessor ID register (wCID, register 0 of CP1). Therefore this adds an explicit check for the presence and correct wCID value, before enabling iWMMXt capabilities. As a bonus, also print the iWMMXt version of a detected coprocessor. This has been tested to properly detect iWMMXt presence/absence on: - PJ4, CPUID 0x560f5815, wCID 0x56052001: Marvell Dove, iWMMXt v2 - PJ4B, CPUID 0x561f5811: Marvell Armada 370, no iWMMXt - PJ4B, CPUID 0x562f5841, wCID 0x56052001: Marvell Armada 1500, iWMMXt v2 - PJ4B, CPUID 0x562f5842: Marvell Armada XP, no iWMMXt Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Tested-by: Kevin Hilman <khilman@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/kernel/pj4-cp0.c34
1 files changed, 33 insertions, 1 deletions
diff --git a/arch/arm/kernel/pj4-cp0.c b/arch/arm/kernel/pj4-cp0.c
index 12352cd30ab2..8153e36b2491 100644
--- a/arch/arm/kernel/pj4-cp0.c
+++ b/arch/arm/kernel/pj4-cp0.c
@@ -72,6 +72,33 @@ static void __init pj4_cp_access_write(u32 value)
: "=r" (temp) : "r" (value));
}
+static int __init pj4_get_iwmmxt_version(void)
+{
+ u32 cp_access, wcid;
+
+ cp_access = pj4_cp_access_read();
+ pj4_cp_access_write(cp_access | 0xf);
+
+ /* check if coprocessor 0 and 1 are available */
+ if ((pj4_cp_access_read() & 0xf) != 0xf) {
+ pj4_cp_access_write(cp_access);
+ return -ENODEV;
+ }
+
+ /* read iWMMXt coprocessor id register p1, c0 */
+ __asm__ __volatile__ ("mrc p1, 0, %0, c0, c0, 0\n" : "=r" (wcid));
+
+ pj4_cp_access_write(cp_access);
+
+ /* iWMMXt v1 */
+ if ((wcid & 0xffffff00) == 0x56051000)
+ return 1;
+ /* iWMMXt v2 */
+ if ((wcid & 0xffffff00) == 0x56052000)
+ return 2;
+
+ return -EINVAL;
+}
/*
* Disable CP0/CP1 on boot, and let call_fpe() and the iWMMXt lazy
@@ -80,17 +107,22 @@ static void __init pj4_cp_access_write(u32 value)
static int __init pj4_cp0_init(void)
{
u32 __maybe_unused cp_access;
+ int vers;
if (!cpu_is_pj4())
return 0;
+ vers = pj4_get_iwmmxt_version();
+ if (vers < 0)
+ return 0;
+
#ifndef CONFIG_IWMMXT
pr_info("PJ4 iWMMXt coprocessor detected, but kernel support is missing.\n");
#else
cp_access = pj4_cp_access_read() & ~0xf;
pj4_cp_access_write(cp_access);
- printk(KERN_INFO "PJ4 iWMMXt coprocessor enabled.\n");
+ pr_info("PJ4 iWMMXt v%d coprocessor enabled.\n", vers);
elf_hwcap |= HWCAP_IWMMXT;
thread_register_notifier(&iwmmxt_notifier_block);
#endif